Horizontal Centering of Sampling Point Using Vertical Vernier

2. The apparatus of claim 1, wherein the measurement controller is configured to determine a voltage swing of the data signal from a signal amplitude of a first low-frequency pattern in the data signal a signal amplitude of a second low-frequency pattern in the data signal, and a peak signal amplitude for a transitional data pattern.

3. The apparatus of claim 2, wherein the channel-characteristic parameters are based on (i) a ratio between the peak signal amplitude of the transitional data pattern and one of the signal amplitudes of the first and second low-frequency patterns in the data signal and (ii) the voltage swing of the data signal between the first and second low-frequency patterns in the data signal.

4. The apparatus of claim 2, wherein the voltage swing corresponds to a peak-to-peak voltage swing in the data signal.

5. The apparatus of claim 1, wherein the channel-characteristic parameters correspond to transceiver control codes.

6. The apparatus of claim 5, wherein the measurement controller comprises a look-up table configured to receive the transceiver control codes, and to adjust the pair of decision thresholds according to an output of the lookup table.

7. The apparatus of claim 5, wherein the transceiver control codes comprise feed-forward equalization settings from a transmitter.

8. The apparatus of claim 5, wherein the transceiver control codes comprise continuous time linear equalizer settings from a receiver.

9. The apparatus of claim 1, further comprising a spare sampler configured to measure a vertical opening of the signaling eye for a data pattern by measuring a top of the signaling eye and a bottom of the signaling eye, and wherein the decision thresholds initialized according to the vertical center of the signal eye are based on an equidistant point from the top of the signaling eye and the bottom of the signaling eye.

10. The apparatus of claim 9, wherein at least one of the top and bottom of the signal eye is associated with a transition.

12. The method of claim 11, further comprising determining a voltage swing of the data signal from a signal amplitude of a first low-frequency pattern in the data signal a signal amplitude of a second low-frequency pattern in the data signal, and a peak signal amplitude for a transitional data pattern.

13. The method of claim 12, wherein the channel-characteristic parameters are based on (i) a ratio between the peak signal amplitude of the transitional data pattern and one of the signal amplitudes of the first and second low-frequency patterns in the data signal and (ii) the voltage swing of the data signal between the first and second low-frequency patterns in the data signal.

14. The method of claim 12, wherein the voltage swing corresponds to a peak-to-peak voltage swing in the data signal.

15. The method of claim 11, wherein the channel-characteristic parameters correspond to transceiver control codes.

16. The method of claim 15, wherein the measurement controller comprises a look-up table configured to receive the transceiver control codes, and to adjust the pair of decision thresholds according to an output of the lookup table.

17. The method of claim 15, wherein the transceiver control codes comprise feed-forward equalization settings from a transmitter.

18. The method of claim 15, wherein the transceiver control codes comprise continuous time linear equalizer settings from a receiver.

19. The method of claim 11, further comprising measuring a vertical opening of the signaling eye for a data pattern by measuring a top of the signaling eye and a bottom of the signaling eye, and wherein the decision thresholds initialized according to the vertical center of the signal eye are based on an equidistant point from the top of the signaling eye and the bottom of the signaling eye.

20. The method of claim 19, wherein at least one of the top and bottom of the signal eye is associated with a transition.